This invention relates to a method of manufacturing an electron beam selection electrode, in particular, an aperture grille of a color cathode ray tube.
An aperture grille which is a kind of electron beam selection electrode is formed by laying grid elements on a frame with a predetermined space provided therebetween. Structure of this type of grille is disclosed in Tachikawa et al U.S. Pat. No. 3,638,063. In such an aperture grille a damper wire is provided for preventing vibration and is stretched on a surface of the grid elements laid on the frame. Conventionally, stretching of the damper wire has been only manually carried out, and the following problems have been present. That is, since the damper wire is fine, such that the diameter thereof is 15-30 .mu.m, it is difficult to accurately position the damper wire to a fixing member (so-called spring member) fixed on the frame and weld same thereto. Further, as shown in FIG. 1, upon positioning the damper wire 1 on the fixing member 2 and welding same by an upper electrode 3 and a lower electrode 4 (see FIG. 1A), the damper wire 1 itself is not molten, but the upper electrode 3 as well as the fixing member 2 are molten to cause deformation of both the electrodes because material of the damper wire 1 is tungsten (See FIG. 1B). When a subsequent damper wire 1 is welded using such electrodes 3 and 4 as thus deformed, welding uniformity is greatly deteriorated. Accordingly, the prior method has generated a color cathode ray tube in which there is a possibility of improper beam landing because of inaccuracies in installation of the damper wire 1.